Generation of a decoherence-free entangled state using a radio frequency dressed state

TL;DR

This paper presents a method to generate high-fidelity, decoherence-free entangled states in trapped calcium ions using rf dressed states, achieving long coherence times and surpassing separability thresholds.

Contribution

The authors introduce a novel technique combining rf dressed states and spin-dependent forces to produce decoherence-free entangled states with high fidelity in trapped ions.

Findings

Achieved a fidelity of 0.68 for rf entangled states with over 200 ms coherence time.

Generated a qutrit-qutrit entangled state with a fidelity of 0.77.

Demonstrated the method's ability to produce states exceeding separability thresholds.

Abstract

We propose the generation of entangled states with trapped calcium ions using a combination of an rf dressed state and a spin dependent force. Using this method, a decoherence-free entangled state of rf qubits can be directly generated and ideally its fidelity is close to unity. We demonstrate an rf entangled state with a fidelity of 0.68, which has a coherence time of more than 200 ms by virtue of the fact that it is an eigenstate with energy gaps between adjacent levels.Using the same technique, we also produce a qutrit-qutrit entangled state with a fidelity of 0.77, which exceeds the threshold value for separability of 2/3.